Oversize chambers has been a problem in the 45Colt cartridge with a lot of manufacture's including Smith. When I was searching for a 45 mountain gun I purposely brought along gage pins from .451 to .454. When I found mine it wouldn't accept a .453 sized pin. As I recall reading all the previous Anacondas suffered from this and some gunsmith actually built and fitted new cylinders. Still have the pins in my car ready to go if I ever see one and hopefully Colt will have fixed the problem in a new release.
This may have been the first revolvers, or at least they were made in the first year that S&W changed their 45LC cylinder ball mouths from 0.455 to 0.452
These are my phone notes with Doug Brassard of S&W Customer Service. This gentleman was extremely knowledgeable about the history and products of S&W, only worked their for a short time. I was glad to talk to him.
25 March 1991 Talk with Doug Brassard
I asked Doug about the chamber dimensions that were allowable for the 45 Colt. This was in reference to a discussion I had with Lee Precision about their carbide crimp die sizing all the 45 Colt cases with .454 diameter bullets. Doug said that Smith and Wesson belongs to SAAMI and receives their specifications. Only American ammo and gun manufacturers belong to SAAMI. In fact PMC once asked him to send them all of his SAAMI specification books. He told them to go join SAAMI. Anyway, SAAMI allows a rear diameter of .4862 nominal plus .004 and .4806 plus .004 for rear of the 45 Colt chamber. When I asked him about the 45 Colt ball chamber throat diameters he said that they used to be .4545 to .4565 but now they were .452 . Smith and Wesson has its own standards for the barrel dimensions for the 45 Colt and they are : one turn in 20, 5 groove, lands .444 -0.0 + .0012, groove .451 - 0.0 + .0017. For the 45 ACP it is a 6 groove barrel, 1 turn in 15 inches, lands of .443 -0.0 +.0012 and grooves of .450 -0.0 and +.0017. Interestingly enough the SAAMI specifications for 45 ACP lead bullets and jacketed bullets are different. Jacketed specs are .452 -.003 and lead bullets .453 -.003.
Of course S&W is free to change their specs as SAAMI is a voluntary organization and has zero law enforcement powers. What S&W was doing in the 1980's could be entirely different thirty years later. These specification groups, and there are lots of them (National Fire Code, National Electric Code, etc) want dues, and therefore publish best practices, but don't go after anyone
. Their codes only have the force of law if Governments adopt them, and make them law. You can find structural and electrical codes adopted by local cities, but it is the local Attorney General who enforces their practice.
I remember calling Marlin and asking why their 44 Magnum rifle barrels were .431 when cast bullets are .429, and why the twist was 1:20, which would not stabilize bullets greater than 240 grain. New Haven Marlin said the dimensions were because of SAMMI. Colt may have said the same thing about their huge chamber mouths, but I don't remember. I have read a number of articles in the in print press, which are simply infomercials of the 6.8 Western, which is infinitesimally different from the 270 WSM cartridges. (And that is planned obsolescence, no different from your IPhones) In print writers claim the 270 Win can't shoot straight because the bullet is wobbling its way down the tube. However the 6.8 Western is so much better than the 270 Win because the manufacturer is using a tighter throats than the 270 Win. They also claim that manufacturers cannot tighten the throat of a 270 Win chamber because SAAMI won't let them. Therefore, to get the accuracy shooters want, industry has to create entirely new cartridges, which require new rifles, new cases, new dies, new etc, etc. . Well that story is an out and out lie. Manufacturers can do what they want, and often, such as Colt, are totally clueless about what the market wants, and use SAAMI as an excuse for their lethargy and incompetence.
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